Grain surface moisture drying method and drying box

Abstract

This invention discloses a method and drying chamber for drying the surface moisture of grain. The method includes the following steps: S1, feeding the grain to be dried into the drying chamber, and introducing a high-speed airflow into the air inlet of the drying chamber to dry the surface of the grain; S2, acquiring the real-time air temperature and humidity at the air outlet and air inlet of the drying chamber to calculate the real-time absolute humidity at the air outlet and air inlet; S3, calculating the real-time mass flow rate of the incoming air at the air inlet of the drying chamber; S4, calculating the real-time evaporation rate of the drying chamber; S5, calculating the real-time surface moisture index (SWI) of the grain in the drying chamber; S6, when the SWI decreases to reach a first set threshold, determining that the surface moisture of the grain in the drying chamber has been dried, stopping the introduction of the high-speed airflow into the air inlet of the drying chamber, and ending the drying process. This invention provides a method and drying chamber for drying the surface moisture of grain, which can automatically dry the surface moisture of grain and monitor the surface moisture of the grain in the drying chamber in real time.

Description

Technical Field

[0001] This invention relates to the field of grain processing. More specifically, this invention relates to a method for drying surface moisture in grain and a drying oven. Background Technology

[0002] The impact of surface moisture on grain during transportation: high moisture content in grain acts as a "mobile risk source," significantly increasing the probability of loss, quality deterioration, and even safety accidents during transport.

[0003] According to the latest guidelines issued by the National Food and Strategic Reserves Administration, shippers must properly handle high-moisture grains before transportation. This is mainly because high moisture content can cause the following three core risks during transportation:

[0004] 1. This triggers a vicious cycle of "heating-molding," which is the most significant risk. When grain moisture content is excessive, its respiration becomes abnormally vigorous, continuously releasing heat and moisture. This process deteriorates rapidly in enclosed transport vehicles (such as ship holds and train carriages), creating a vicious cycle of "high temperature → high humidity → faster mold growth."

[0005] Local hotspots can form rapidly: even a small amount of high-moisture grain mixed in can act as a "fuse." A study on soybeans showed that burying 120 kilograms of high-moisture soybeans in a grain pile with safe moisture content would cause the hotspot to start generating heat in just one day, with the temperature rise in the hotspot area reaching 2.26°C per day.

[0006] Mold proliferates rapidly: High temperature and high humidity environments are breeding grounds for mold. Studies have shown that rice with an initial moisture content of over 18% will have a significantly higher mold count than grain with a safe moisture content after only 15 days of storage and transportation under medium to high temperature conditions.

[0007] 2. Both internal condensation and external moisture absorption during transportation, along with temperature and humidity changes, exacerbate the risks associated with high-moisture grains.

[0008] Internal condensation: When the outside temperature drops, moisture in the warm, humid air inside the transport vehicle condenses into water droplets on the surface or top of the grain pile. This process is called "condensation." This makes the grain in some areas even wetter, creating new centers of mold growth.

[0009] External moisture: The "Technical Guidelines for Reducing Losses During Grain Transportation" specifically emphasizes that the sealing of vehicles and ship holds must be checked before transportation to ensure there are no leaks, snow, or moisture. Rain, snow, or water splashing during transport, or passing through flooded areas, can directly cause the grain to become damp.

[0010] 3. Leads to an overall decline in grain quality:

[0011] Moisture not only affects microorganisms, but also directly damages the quality of the grain itself.

[0012] Nutritional quality loss: High moisture content accelerates the deterioration of grains. For example, the fatty acid value of rice (an important indicator of freshness) increases significantly with increasing initial moisture content. The protein and oil content of soybeans may also decrease as a result.

[0013] Deterioration in processing and eating quality: High moisture content also affects the taste of grains. Studies have found that after storage and transportation, rice with high moisture content will have increased hardness and decreased stickiness when cooked, directly leading to a decline in eating quality.

[0014] Therefore, it is necessary to design a grain drying method that can quickly remove surface moisture from grains without damaging them. Summary of the Invention

[0015] The purpose of this invention is to address the above-mentioned problems by providing a method and drying box for drying the surface moisture of grains, which can automatically dry the surface moisture of grains and monitor the surface moisture of grains in real time within the drying box.

[0016] To achieve these objectives and other advantages according to the present invention, a method for drying surface moisture of grain is provided, comprising the following steps:

[0017] S1. The grain to be dried is sent into the drying box. The drying box is equipped with an air outlet and an air inlet at the top and bottom. A high-speed airflow is sent into the air inlet of the drying box. The high-speed airflow forms a continuous airflow from bottom to top in the drying box to dry the surface of the grain to be dried.

[0018] S2. Obtain the real-time air temperature and air humidity at the air outlet and air inlet of the drying oven respectively, so as to calculate the real-time absolute humidity at the air outlet and air inlet of the drying oven.

[0019] S3. Calculate the real-time mass flow rate of the air inlet at the drying oven. ;

[0020] S4. Calculate the real-time evaporation rate of the drying oven:

[0021] (1)

[0022] in, This refers to the real-time evaporation rate of the drying oven. This refers to the real-time absolute humidity at the air outlet of the drying oven. This refers to the real-time absolute humidity at the air inlet of the drying oven.

[0023] S5. Calculate the real-time surface moisture index of the grain inside the drying oven:

[0024] (2)

[0025] in, The real-time surface moisture index of the grain inside the drying oven; This represents the maximum real-time evaporation rate of the drying oven.

[0026] S6, when When the moisture level drops to the first set threshold, it is determined that the surface moisture of the grain inside the drying chamber has dried, and the high-speed airflow into the air inlet of the drying chamber is stopped, thus ending the drying process.

[0027] Furthermore, in the aforementioned method for drying surface moisture of grain, the method for calculating the real-time absolute humidity at the air outlet and air inlet of the drying chamber in step S2 is as follows:

[0028] Calculate saturated water vapor pressure :

[0029] (3)

[0030] in, Real-time temperature;

[0031] Calculate real-time water vapor pressure :

[0032] (4)

[0033] in, Relative humidity refers to the real-time air humidity at the air outlet or air inlet of the drying oven.

[0034] Calculate absolute humidity:

[0035] (5)

[0036] in, for or ; Atmospheric pressure.

[0037] Furthermore, in the aforementioned method for drying surface moisture in grains, the real-time mass flow rate of the incoming air at the air inlet of the drying chamber in step S3 is... The calculation method is as follows:

[0038] Calculate real-time air density :

[0039] (6)

[0040] in, The gas constant for dry air is 287.05 J / (kg·K);

[0041] calculate :

[0042] (7)

[0043] in, This refers to the real-time airflow rate at the air inlet of the drying oven.

[0044] Furthermore, in the aforementioned method for drying surface moisture of grain, the step between steps S5 and S6 further includes, when... If the moisture content on the grain surface is less than the second set threshold, the remaining drying time T is predicted, where the second set threshold is greater than the first set threshold.

[0045] (8)

[0046] in, The calculation method for dynamically calculating the attenuation constant is as follows:

[0047] (9)

[0048] in, Set a threshold for the second one; The current moment; for The moment when the temperature drops to the second set threshold.

[0049] The present invention also provides a grain drying box, employing the above-mentioned drying method, characterized in that it includes:

[0050] The enclosure has a support frame at its lower end, and air inlets and outlets are respectively provided at the upper and lower ends of the enclosure. A door is provided on one side of the enclosure.

[0051] A grain storage rack is installed horizontally within the box and can slide through the box door to the outside of the box.

[0052] An air inlet equalization plate is disposed inside the box and located below the grain placement rack;

[0053] An air supply device for supplying air into the flow equalization chamber;

[0054] A wind speed sensor is installed at the air outlet of the air supply device;

[0055] The first temperature and humidity sensor is located at the air inlet of the enclosure.

[0056] The second temperature and humidity sensor is located at the air outlet of the air supply device.

[0057] Furthermore, in the aforementioned grain drying box, the air supply device is an axial flow fan, the bottom wall of the box has an opening in the middle, the axial flow fan is embedded in the opening, and the bottom wall of the box is also provided with a water collection trough, on which multiple drainage holes are evenly distributed.

[0058] Furthermore, in the aforementioned grain drying box, the water collection trough slopes from the center to the edge, and the drain hole is located at its edge.

[0059] Furthermore, in the grain drying box, the air inlet equalization plate protrudes upward in the middle and has an annular water collection trough at its upper edge, with multiple drainage holes evenly distributed in the annular water collection trough.

[0060] Furthermore, in the aforementioned grain drying box, the surface of the air inlet equalization plate is coated with a hydrophilic coating.

[0061] Furthermore, in the aforementioned grain drying box, the grain placement rack includes:

[0062] The bracket body has two drawer slides spaced apart at its lower end, and is slidably connected to the box body through the drawer slides.

[0063] Multiple U-shaped positioning frames are spaced apart on the support body, with the openings of the positioning frames facing the door;

[0064] Multiple trays, each having an outwardly turned edge and a mesh structure, can be placed in any of the positioning frames;

[0065] A collection box, which is detachably mounted at the lower end of the support body, has a mesh structure.

[0066] The beneficial effects of this invention are:

[0067] 1. In the grain drying method of the present invention, by acquiring the humidity data of the air inlet and outlet of the box and combining it with the air volume of the air inlet, the evaporation rate and surface moisture index of the grain in the box are calculated, and the surface moisture of the grain in the drying box is monitored in real time, and the drying is automatically completed, so as to better control the drying time and eliminate the need for multiple manual confirmations.

[0068] 2. In the grain drying method of the present invention, the remaining drying time can be predicted, so that the staff can make better plans.

[0069] 3. In the grain drying box of the present invention, air is blown upward by the air supply device, and the continuous airflow from bottom to top is forced through the grain layer to efficiently remove the free moisture on the surface of the grain after washing or cutting.

[0070] 4. In the grain drying box of the present invention, the grain placement rack prevents the grain from being placed in the drying box, thus solving the problems of convenient loading and unloading and uniform multi-layer placement.

[0071] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0072] Figure 1 This is a flowchart of the grain surface moisture drying method described in this invention;

[0073] Figure 2 This is a schematic diagram of the structure of the grain drying box described in this invention;

[0074] Figure 3 This is a schematic diagram of the structure of the grain drying box described in this invention;

[0075] Figure 4 for Figure 3 Enlarged view of point A in the middle;

[0076] Figure 5 for Figure 3 Enlarged view of section B in the middle. Detailed Implementation

[0077] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0078] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified. In the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0079] like Figure 1 As shown, an embodiment of the present invention provides a method for drying the surface moisture of grain, comprising the following steps:

[0080] S1. The grain to be dried is sent into the drying box. The drying box is equipped with an air outlet and an air inlet at the top and bottom. A high-speed airflow is sent into the air inlet of the drying box. The high-speed airflow forms a continuous airflow from bottom to top in the drying box to dry the surface of the grain to be dried.

[0081] S2. Obtain the real-time air temperature and humidity at the air outlet and air inlet of the drying oven, respectively, to calculate the real-time absolute humidity at the air outlet and air inlet of the drying oven. The method for calculating absolute humidity is as follows:

[0082] Calculate saturated water vapor pressure :

[0083] (3)

[0084] in, Real-time temperature;

[0085] Calculate real-time water vapor pressure :

[0086] (4)

[0087] in, Relative humidity refers to the real-time air humidity at the air outlet or air inlet of the drying oven.

[0088] Calculate absolute humidity:

[0089] (5)

[0090] in, for or ; Atmospheric pressure.

[0091] S3. Calculate the real-time mass flow rate of the air inlet at the drying oven. The calculation method is as follows:

[0092] Calculate real-time air density :

[0093] (6)

[0094] in, The gas constant for dry air is 287.05 J / (kg·K);

[0095] calculate :

[0096] (7)

[0097] in, This refers to the real-time airflow rate at the air inlet of the drying oven.

[0098] S4. Calculate the real-time evaporation rate of the drying oven:

[0099] (1)

[0100] in, This refers to the real-time evaporation rate of the drying oven. This refers to the real-time absolute humidity at the air outlet of the drying oven. This refers to the real-time absolute humidity at the air inlet of the drying oven.

[0101] S5. Calculate the real-time surface moisture index of the grain inside the drying oven:

[0102] (2)

[0103] in, The real-time surface moisture index of the grain inside the drying oven; This represents the maximum real-time evaporation rate of the drying oven.

[0104] S6, when When the moisture level drops to the first set threshold, it is determined that the surface moisture of the grain inside the drying chamber has dried, and the high-speed airflow into the air inlet of the drying chamber is stopped, thus ending the drying process.

[0105] In this embodiment, a continuous airflow + high-speed airflow environment is formed in the drying box, which forces convection heat transfer and significantly accelerates the evaporation rate of grain surface moisture. The evaporation rate of grain surface is inferred by measuring the temperature and humidity changes at the air inlet and outlet. The surface moisture index (SWI) driven by the physical mechanism realizes calibration-free, non-contact, low-cost, adaptive real-time monitoring of surface moisture and intelligent judgment of drying endpoint, which is perfectly compatible with grain pre-drying equipment with sliding supports.

[0106] Preferably, in another embodiment of the present invention, the method for drying surface moisture of grain further includes, between S5 and S6, a step of... If the moisture content on the grain surface is less than the second set threshold, the remaining drying time T is predicted, where the second set threshold is greater than the first set threshold.

[0107] (8)

[0108] in, Set a threshold for the first one; The calculation method for dynamically calculating the attenuation constant is as follows:

[0109] (9)

[0110] in, Set a threshold for the second one; The current moment; for The moment when the temperature drops to the second set threshold.

[0111] In this embodiment, as the drying process proceeds, It continues to decline. The changes during the entire grain drying process exhibit a three-stage characteristic. During the period from the initial moisture level down to the second set threshold, a large amount of free water exists on the grain surface, the evaporation rate approaches its theoretical maximum, the absolute humidity difference between the inlet and outlet remains stable, and the evaporation rate is constant. Once the water level drops to between the second and first set thresholds, the surface free water is essentially removed, leaving only adsorbed water. The evaporation rate is then limited by the diffusion of internal moisture to the surface. After the water level drops to a first predetermined threshold, evaporation becomes controlled by the internal moisture diffusion rate, making moisture migration increasingly difficult. The method described in this embodiment can... When the price drops to between the second and first set thresholds, exponential decay prediction is used, and the decay constant is dynamically calculated. Real-time estimation of remaining drying time enables adaptive prediction and control of the grain surface moisture drying process, combining physical interpretability, engineering simplicity, and practical value.

[0112] like Figures 2-4 As shown, an embodiment of the present invention provides a grain drying box, comprising:

[0113] The box body 1 has a support frame 2 at its lower end. The upper and lower ends of the box body 1 are respectively provided with an air inlet 3 and an air outlet 4, and a box door is provided on one side.

[0114] The grain storage rack 5 is horizontally slidable inside the box 1 and can slide through the box door to the outside of the box 1;

[0115] An air inlet equalization plate 6 is disposed inside the housing 1 and located below the grain placement rack 5;

[0116] Air supply device 7, which is used to supply air into the flow equalization cavity;

[0117] Wind speed sensor 8 is installed at the air outlet 4 of the air supply device 7;

[0118] The first humidity sensor 9 is located at the air inlet 3 of the housing 1;

[0119] The second humidity sensor 10 is located at the air outlet 4 of the air supply device 7.

[0120] In this embodiment, when using the drying oven, open the oven door, pull out the grain rack 5, place the washed or harvested grain on the grain rack 5, push the grain rack 5 back into the oven body 1, and close the oven door. Turn on the air supply device 7, and air is supplied upwards through the air supply device 7, forming a continuous airflow from bottom to top in the oven body 1. The airflow is evenly distributed by the air inlet equalization plate 6, avoiding excessively fast local airflow or the formation of eddies. This ensures that all grains on the grain rack 5 come into contact with the airflow, and the airflow passes through the grain and is discharged through the air outlet. In this process, the continuous airflow from bottom to top forces the grain layer through, carrying away the moisture on the surface of the grain.

[0121] Furthermore, during the operation of the drying oven, the real-time humidity at the air inlet 3 and air outlet 4 of the oven body 1 is obtained by the first humidity sensor 9 and the second humidity sensor 10, respectively, i.e., the absolute humidity of the air entering and exiting the oven body 1. The wind speed at the air outlet 4 of the air supply device 7 is obtained by the wind speed sensor. The air flow rate at the air inlet 3 of the oven body 1 can be calculated by multiplying the wind speed by the area of ​​the air outlet 4 of the air supply device 7. Then, the air flow rate at the air inlet 3 is multiplied by the air density to obtain the air mass flow rate at the air inlet 3.

[0122] First, calculate the real-time evaporation rate:

[0123] Real-time evaporation rate = air mass at the air inlet of the box × (absolute humidity of the outlet air - absolute humidity of the inlet air);

[0124] Calculate the surface moisture index of the grain inside container 1:

[0125] Surface moisture index = Real-time evaporation rate / Maximum evaporation rate;

[0126] The surface moisture index is generally set at 10-15%. The threshold for the surface moisture index is set according to different types of grains. When the surface moisture index of the grain in the calculation box 1 drops to the set threshold, it is determined that the surface moisture of the grain has dried. At this time, the air supply device 7 stops working, and the drying of the surface moisture of the grain is completed. Therefore, it is not necessary for the staff to constantly observe and confirm the drying status of the grain surface water during the drying process.

[0127] In this embodiment, by acquiring the humidity data of the air inlet 3 and air outlet 4 of the box 1, and combining it with the air volume of the air inlet 3, the evaporation rate and surface moisture index of the grain in the box 1 are calculated, and the surface moisture of the grain in the drying box is monitored in real time to better control the drying time.

[0128] Preferably, in another embodiment of the present invention, the air supply device 7 is an axial flow fan, the bottom wall of the housing 1 has an opening in the middle, the axial flow fan is embedded in the opening, and the bottom wall of the housing 1 is also provided with a water collection tank 11, on which a plurality of drainage holes are evenly distributed.

[0129] In this embodiment, the air supply device 7 uses an axial flow fan. With the same power and volume, the axial flow fan can deliver a much larger volume of air than a centrifugal fan, making it particularly suitable for high-flow ventilation scenarios such as drying the surface moisture of grains. Moreover, after grains are placed on the grain rack 5, water droplets on the grains fall into the axial flow fan, pass directly through the fan, and fall outside the housing 1 or onto the blades of the axial flow fan, without affecting the fan.

[0130] In actual use, water droplets may condense on the air inlet equalization plate 6 and the grain placement rack 5. Therefore, a water collection trough 11 is provided on the bottom wall of the box 1 to collect water droplets and discharge them downwards from the drain hole on the water collection trough 11 into the box 1.

[0131] Preferably, in another embodiment of the present invention, the water collection tank 11 is inclined from the middle to the edge, and the drain hole is located at its edge.

[0132] In this embodiment, the water collection tank 11 is inclined from the middle to the edge to form a conical surface. The water in the water collection tank 11 flows to the edge and finally flows out from the drain hole.

[0133] Preferably, in another embodiment of the present invention, the air inlet equalization plate 6 protrudes upward in the middle and has an annular water collection groove 12 at its upper edge, and the annular water collection groove 12 has a plurality of drainage holes evenly distributed in it.

[0134] In this embodiment, the air inlet equalization plate 6 is directly set below the grain placement rack 5. After the water droplets on the grain on the grain placement rack 5 fall onto the air inlet equalization plate 6, they flow towards its edge under the action of gravity and finally fall into the annular water collection trough 12. Finally, they fall from the drain hole into the annular water collection trough 12.

[0135] Preferably, as another embodiment of the present invention, the surface of the air inlet flow equalization plate 6 is coated with a hydrophilic coating.

[0136] In this embodiment, a hydrophilic coating is sprayed onto the surface of the air intake flow equalization plate 6. The hydrophilic coating prevents water from forming water droplets on the surface of the air intake flow equalization plate 6, and instead causes water to quickly spread into a water film and flow into the annular water collection tank 12.

[0137] Preferably, as another embodiment of the present invention, such as Figure 4 As shown, the grain storage rack 5 includes:

[0138] The support body 13 has two drawer slides spaced apart at its lower end, and is slidably connected to the box body 1 through the drawer slides;

[0139] Multiple U-shaped positioning frames 14 are spaced apart on the bracket body 13, and the openings of the positioning frames 14 face the door.

[0140] Multiple trays 15, each having an outwardly turned edge and a mesh structure, are placed in any of the positioning frames 14.

[0141] In this embodiment, a tray 15 is placed in each positioning frame 14. The tray 15 should be removable for easy cleaning. The tray 15 serves as a grain container and has a mesh structure, allowing gas to flow freely through the gaps between the grains after they are poured into the tray 15.

[0142] Preferably, as another embodiment of the present invention, such as Figure 5 As shown, it also includes:

[0143] The collection box 16 is detachably disposed at the lower end of the support body 13, and the collection box 16 has a mesh structure.

[0144] In this embodiment, since some broken grains or debris may fall off the grain on the grain rack 5, a collection box 16 is provided at the lower end of the grain rack 5 for processing. In actual use, when the grain rack is pulled out, the collection box 16 is pulled out along with it. The collection box 16 has a mesh structure, which does not affect the upward movement of airflow.

[0145] The collection box 16 and the support body 13 are detachable, specifically, as follows: Figure 5 As shown, multiple threaded rods can be installed at the lower end of the bracket body 13. The threaded rods pass through the collection box 16, and nuts are installed on the threaded rods to support the collection box 16.

[0146] Preferably, as another embodiment of the present invention, it further includes:

[0147] A canopy 17 is provided above the box body 1, with an opening at the top.

[0148] In this embodiment, a canopy 17 is installed above the box 1 to protect the box 1 from rain, so that the box 1 can be used outdoors and can be used directly in the fields.

[0149] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A method for drying the surface moisture of grain, characterized in that, Includes the following steps: S1. The grain to be dried is sent into the drying box. The drying box is equipped with an air outlet and an air inlet at the top and bottom. A high-speed airflow is sent into the air inlet of the drying box. The high-speed airflow forms a continuous airflow from bottom to top in the drying box to dry the surface of the grain to be dried. S2. Obtain the real-time air temperature and air humidity at the air outlet and air inlet of the drying oven respectively, so as to calculate the real-time absolute humidity at the air outlet and air inlet of the drying oven. S3. Calculate the real-time mass flow rate of the air inlet at the drying oven. ; S4. Calculate the real-time evaporation rate of the drying oven: （1）； in, This refers to the real-time evaporation rate of the drying oven. This refers to the real-time absolute humidity at the air outlet of the drying oven. This refers to the real-time absolute humidity at the air inlet of the drying oven. S5. Calculate the real-time surface moisture index of the grain inside the drying oven: （2）； in, The real-time surface moisture index of the grain inside the drying oven; This represents the maximum real-time evaporation rate of the drying oven. S6, when When the moisture level drops to the first set threshold, it is determined that the surface moisture of the grain inside the drying chamber has dried, and the high-speed airflow into the air inlet of the drying chamber is stopped, thus ending the drying process.

2. The method for drying surface moisture of grain as described in claim 1, characterized in that, The method for calculating the real-time absolute humidity at the air outlet and air inlet of the drying oven in S2 is as follows: Calculate saturated water vapor pressure : （3）； in, Real-time temperature; Calculate real-time water vapor pressure : （4）； in, Relative humidity refers to the real-time air humidity at the air outlet or air inlet of the drying oven. Calculate absolute humidity: （5）； in, for or ; Atmospheric pressure.

3. The method for drying surface moisture of grain as described in claim 2, characterized in that, Real-time airflow mass flow rate at the air inlet of the S3 drying oven The calculation method is as follows: Calculate real-time air density : （6）； in, The gas constant for dry air is 287.05 J / (kg·K); calculate : （7）； in, This refers to the real-time airflow rate at the air inlet of the drying oven.

4. The method for drying surface moisture of grain as described in claim 1, characterized in that, Between S5 and S6, there is also, when If the moisture content on the grain surface is less than the second set threshold, the remaining drying time T is predicted, where the second set threshold is greater than the first set threshold. （8）； in, The calculation method for dynamically calculating the attenuation constant is as follows: （9）； in, Set a threshold for the second one; The current moment; for The moment when the price drops to the second set threshold.

5. A grain drying box, employing the drying method as described in any one of claims 1-4, characterized in that, include: The enclosure has a support frame at its lower end, and air inlets and outlets are respectively provided at the upper and lower ends of the enclosure. A door is provided on one side of the enclosure. A grain storage rack is installed horizontally within the box and can slide through the box door to the outside of the box. An air inlet equalization plate is disposed inside the box and located below the grain placement rack; An air supply device for supplying air into the flow equalization chamber; A wind speed sensor is installed at the air outlet of the air supply device; The first temperature and humidity sensor is located at the air inlet of the enclosure. The second temperature and humidity sensor is located at the air outlet of the air supply device.

6. A grain drying box as described in claim 5, characterized in that, The air supply device is an axial flow fan. The bottom wall of the housing has an opening in the middle, and the axial flow fan is embedded in the opening. The bottom wall of the housing is also provided with a water collection tank, and the water collection tank has multiple drainage holes evenly distributed on it.

7. A grain drying box as described in claim 6, characterized in that, The water collection tank slopes from the center to the edge, and the drain hole is located at its edge.

8. A grain drying box as described in claim 6, characterized in that, The air inlet flow distribution plate has an upward protrusion in the middle, and an annular water collection groove is provided at its upper edge, with multiple drainage holes evenly distributed in the annular water collection groove.

9. A grain drying box as described in claim 8, characterized in that, The surface of the air intake flow distribution plate is coated with a hydrophilic coating.

10. A grain drying box as described in claim 5, characterized in that, The grain storage rack includes: The bracket body has two drawer slides spaced apart at its lower end, and is slidably connected to the box body through the drawer slides. Multiple U-shaped positioning frames are spaced apart on the support body, with the openings of the positioning frames facing the door; Multiple trays, each having an outwardly turned edge and a mesh structure, can be placed in any of the positioning frames; A collection box, which is detachably mounted at the lower end of the support body, has a mesh structure.

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